University of Wisconsin - Extension

Wisconsin's natural resources make the state an ideal place for outdoor recreation. When you hike, camp, hunt, fish or spend time outdoors, it is possible to encounter plants or animals that might cause problems. While poisonous plants, wild animals, and swarms of biting insects do exist in Wisconsin, the risk of meeting them is actually quite low. In most cases, you can avoid these natural hazards all together, or handle them easily.

One that is nearly impossible to avoid is the mosquito. With concerns about West Nile Virus focusing attention on the mosquito as more than just a pesky insect, knowing more about this insect can help protect you and your family. University of Wisconsin-Extension offers a publication, "Outdoor Hazards in Wisconsin: A Guide to Noxious Insects, Plants and Wildlife" (G3564), which can help you recognize, avoid and cope with potential problems caused by a variety Wisconsin wildlife, plants and insects.

Wisconsin's wildlife includes more than 450 species of birds, mammals, reptiles and amphibians. In order to cover this diversity, the publication was co-written by University of Wisconsin-Madison/Extension entomology outreach specialist Phil Pellitteri, wildlife ecology specialist Scott Craven, and Robert Newman, professor emeritus of horticulture.

According to Pellitteri, there are more than 10,000 different insects, spiders, and related creatures that you could meet during a summer walk in Wisconsin. Over 95 percent of these are completely harmless; however, less than one percent of the rest seem to go out of their way to torment people.

Insects and other invertebrates attack people for two reasons: to obtain food or to defend themselves. Blackflies, ticks, mosquitoes, chiggers, deer flies and horse flies require animal or human blood as food. Females use the protein from blood to make eggs. Any other bite or sting is a defensive or protective reaction by the insect.

There are more than 50 mosquito species living in Wisconsin, Pellitteri says. And all females of the species require a blood meal to breed. The most notorious mosquitoes come from the genus Aedes-the floodwater mosquitoes. If a pond or riverbank dries up, their eggs can remain dormant for months or years until they again come into contact with water. It takes about two weeks after water is available for the adults to appear, and up to 100 mosquitoes can emerge per square foot of water surface per day in good breeding habitat. More than 60 percent of these adults will migrate approximately 10 to 20 miles from their breeding site in search of a blood meal. Female mosquitoes will live for three to six weeks and can take multiple blood meals during this time.

Mosquitoes are most active under low light conditions, yet some are "day biters." Winds above 10 miles per hour force mosquitoes to land and rest; when the winds die down, mosquitoes again become active. Avoid brushy, shaded sites, which have the low light and poor air movement that attracts mosquitoes. Temperatures below 50 degrees F prevent mosquitoes from flying, but it usually takes three or four killing frosts to end the mosquito season.

Mosquitoes use carbon dioxide, lactic acid, and heat to find their hosts. When you are more active, you give off more of these attractants. Individuals differ in both their attractiveness to mosquitoes and the way they react to a bite. Dark colors and some fragrances also attract certain mosquitoes.

Even if you sit on a sunny, windy hillside and wear light-colored clothing, you can still be bitten by a mosquito. Other than covering up, the only practical way to deal with mosquitoes is to use a repellent spray, cream, or lotion. The active ingredient in such repellents is usually DEET (N, N-diethyl-meta toluamide), which does not kill mosquitoes, but prevents them from finding you. Read the label. Not all repellents are to be used on skin, and concentrated repellents should not be used on small children. Some repellents will dissolve or stain watch crystals, glasses and painted or varnished surfaces on fishing rods, cars, etc. Most repellents last one to five hours, depending on the amount of sweating or rubbing that occurs. Mosquito netting (23 to 26 meshes per inch) may come in handy for overnight trips.

The wound of a mosquito bite is minor. The intense itching and swelling is an allergic response to the mosquito's salivary secretions. Various treatments such as rubbing alcohol or mild ammonia will help relieve itching. Although mosquitoes transmit many serious diseases throughout the world, the only mosquito-borne disease seen regularly in Wisconsin is LaCrosse encephalitis, which can cause complications in children under 12 years old. Recent concerns about West Nile Virus also make guarding against mosquito bites a matter of good health.

"Outdoor Hazards in Wisconsin: A Guide to Noxious Insects, Plants and Wildlife" (G3564) and other publications are available from your county UW-Extension office or from Cooperative Extension Publications at 608-262-3346 or toll free 877-947-7827 (WIS-PUBS). The publications can also be viewed online at http://www1.uwex.edu/ces/pubs/index.cfm .